1. Field of the Invention
The present invention relates to a radiographic image capture system and method that perform capture of radiographic images represented by radiation that has been emitted from a radiation source and has passed through a subject.
2. Description of the Related Art
In recent years, radiation detectors such as a flat panel detector (FPD), in which a radiation-sensitive layer is placed on a thin-film transistor (TFT) active matrix substrate and which can convert radiation directly into digital data, have been put into practical use. Portable radiographic imaging devices (hereinafter also called “electronic cassettes”) that use these radiation detectors to detect applied radiation and capture radiographic images expressed by the radiation have also been put into practical use. Methods of converting the radiation in the radiation detectors used in the electronic cassettes include an indirect conversion method, in which a scintillator is used to convert the radiation into light and thereafter a semiconductor layer of a photodiode or the like is used to convert the light into electric charges, and a direct conversion method, in which a semiconductor layer of amorphous selenium or the like is used to convert the radiation into electric charges. There exist various types of materials that can be used for the semiconductor layer in each of these methods.
In this way, radiographic image capture systems are becoming increasingly digitized and are undergoing a transition from film and imaging plates to systems using radiation detectors.
Incidentally, in performing full-length lower-extremity imaging and whole-spine imaging for the purpose of bone measurements and so forth to capture images for medical use, the imaging site of the subject covers a wide range, so it is necessary to perform long-length (elongated) imaging in order to grasp the whole. In order to perform such long-length imaging, there is known a radiographic image information recording and reading device in which plural photostimulable phosphor sheets are arranged such that they partially overlap each other and which performs capture of elongated radiographic images (e.g., see Japanese Patent Application Laid-Open No. 3-287249).
Further, in image capture systems using a radiation detector, there is known a radiographic imaging apparatus equipped with a parallel moving mechanism, which enables at least either one of an electronic cassette or a subject to move substantially parallel with respect to the body axis direction of the subject, and a linked moving mechanism, which causes a radiation source to move to a position opposing a radiographic image detector so as to link the radiation source to the movement of the radiographic image detector, wherein the radiation source is configured to apply radiation with respect to the radiographic image detector in plural positions in which its position relative to the subject is different (e.g., see JP-A No. 2005-270277).
However, in the technology disclosed in JP-A No. 2005-270277, image capture is performed multiple times in different positions, so a mechanism for moving the electronic cassette becomes necessary, the apparatus becomes larger in scale, and the cost of the apparatus will be high. By interconnecting plural electronic cassettes, long-length imaging can be performed in the same way as with the technology of JP-A No. 3-287249. However, in the case of using a structure that electrically interconnects and synchronizes the radiation generator and each of the electronic cassettes and a structure that synchronizes each of the electronic cassettes with each other, it is necessary to perform capture of a radiographic image by each of the electronic cassettes in synchronization with the timing when the radiation is emitted from the radiation source. For this reason, it is necessary to electrically interconnect the radiation source and the electronic cassettes and also to electrically interconnect each of the plural electronic cassettes to each other, and the configuration for interconnecting the radiation source and the electronic cassettes, the configuration for interconnecting the plural electronic cassettes to each other, and timing control become complicated.